Not applicable.
Not applicable.
Electrical connectors are used in many electronic systems. It is generally easier and more cost effective to manufacture a system on several printed circuit boards which are then joined together with electrical connectors. A traditional arrangement for joining several printed circuit boards is to have one printed circuit board serve as a backplane. Other printed circuit boards, called daughter boards, are connected to the backplane, often with right angle connectors. Conductive traces on the backplane connect to signal contacts in the connectors to route signals between the connectors and thus, between daughter boards.
Connectors are also used in other configurations for interconnecting printed circuit boards and for connecting cables to printed circuit boards. Sometimes, one or more small printed circuit boards are connected to another larger printed circuit board. The larger printed circuit board is called a xe2x80x9cmother boardxe2x80x9d and the printed circuit boards plugged into it are called daughter boards. Also, boards are sometimes aligned in parallel. Connectors used in these applications are sometimes called xe2x80x9cstacking connectorsxe2x80x9d or xe2x80x9cmezzanine connectors.xe2x80x9d
Electrical connector designs are generally required to mirror trends in the electronics industry. In particular, connectors are required to operate at higher signal speeds and to handle more data in the same space (i.e., to have a higher density). To meet the needs of electronic systems, some electrical connectors include shield members. Shield members are used to control impedance and crosstalk between signals so that the signal conductors can be more closely spaced.
Another requirement of electrical connectors is to meet the growing market needs for customized connector systems. One way to address this requirement is with the use of modular connectors. Teradyne Connection Systems of Nashua, N.H., USA pioneered a modular connector system called HD+(copyright), with the modules organized on a stiffener. Each module has multiple columns of signal contacts, such as 15 or 20 columns. The modules are held together on a metal stiffener.
A further requirement of some electrical connectors is redundant signal contacts. One type of electrical connector which provides redundant signal contacts may be referred to as a box connector or a pin and socket connector and includes box-shaped sockets for receiving pins. More particularly, each box-shaped socket includes a base positioned in a first plane of an imaginary box and two prongs positioned orthogonally with respect to the base, along two opposing sides of the box, to form a xe2x80x9cU-shapedxe2x80x9d socket.
Conventional box connectors provide redundant signal contacts since each socket generally wraps around and contacts at least two sides of a pin. However, such connectors tend to be relatively large since the opposing prongs of the sockets are positioned orthogonally with respect to the base. Further, the relatively large size of such sockets limits the spacing between adjacent sockets and the signal conductors extending from the sockets, thereby disadvantageously tending to increase signal crosstalk.
Redundant signal contacts have been used in card edge connectors in which a first printed circuit board having contacts on an edge is plugged into a card edge connector mounted on a second printed circuit board. In one such arrangement, the card edge connector on the second board includes a header in which a plurality of spring contacts are disposed, with each spring contact including two adjacent fingers. Upon insertion of the first printed circuit board into the card edge connector, each edge contact on the first printed circuit board contacts two adjacent spring fingers.
With the foregoing background in mind, it is an object of the invention to provide a high signal speed, high density electrical connector.
It is a further object to provide a connector having redundant signal contacts.
It is also an object to provide a connector utilizing low profile contacts to permit increased spacing between contacts and conductors and also to provide a connector with shields between rows of conductors in order to reduce signal crosstalk.
Yet another object of the invention is to provide a modular connector that allows for easy and flexible manufacture and further allows close and tightly controlled spacing between signal contacts, signal conductors and shields.
The foregoing and other objects are achieved with a connector system that provides electrical connection between circuit boards by mating blade-shaped contacts of a first connector with beam-shaped contacts of a second, modular connector. The modular connector includes a plurality of shield plates mounted in parallel and a plurality of signal conductors, each having a beam-shaped contact positioned substantially parallel to the shield plates. Preferably, each of the beam-shaped contacts includes substantially coplanar and independent beams which are adapted for contacting a common surface of a respective blade-shaped contact.
With this arrangement, a board-to-board connector system is provided with redundant signal contact points, but with higher signal density and/or reduced crosstalk than heretofore achieved with the use of conventional box connectors. This is because the redundant beam contacts of the present invention have a lower profile than conventional box-shaped sockets and contact only a single surface of a low profile blade-shaped contact. In this way, improved signal integrity is provided for high speed signals.
The first connector includes an insulative housing supporting an array of contacts and the second, modular connector includes a complementary array of beam-shaped contacts. Each of the contacts of the first connector has a conductive member at a first end for electrically connecting to a first circuit board and a blade-shaped contact at a second end. Each of the beam-shaped contacts of the second, modular connector is positioned at a first end of a signal conductor which has a conductive element adapted for electrically connecting to a second circuit board at a second end.
The modular connector includes a plurality of shield subassemblies and a corresponding plurality of signal subassemblies, with each shield subassembly/signal subassembly pair providing a module. Multiple modules are stacked in parallel to provide the modular connector.
In one embodiment, each shield subassembly is provided by molding an insulative receptacle over a portion of a shield plate and each signal subassembly is provided by inserting a plurality of signal conductors into a molded insulative member to form a row of signal conductors. Each signal subassembly is attached to a respective shield subassembly to form a module in which the beam-shaped contacts of the signal conductors are positioned substantially parallel to the shield plate.
In one embodiment, each insulative receptacle has a cavity in one side for receiving the beam-shaped contact of a respective signal conductor and a hole in an opposing side in substantial alignment with the cavity. With this arrangement, a blade-shaped contact of the first connector inserted into a hole of the insulative receptacle contacts a respective beam-shaped contact of the second, modular connector.
In accordance with a further aspect of the invention, the insulative receptacles of the shield subassemblies include a second plurality of holes, each providing access to a shield plate, and the first connector includes a plurality of shield contacts. With this arrangement, the connector system provides both signal and shield, or ground electrical interconnections between circuit boards. In this way, reflections caused by impedance discontinuities at the point of mating a two piece connector are reduced.